Whites are a steadily diminishing fraction of the population. In fact, the demographic trends show that they will no longer be the majority of the population, starting sometime about 2050. Jamelle Bouie has a fine essay exploring what this might mean for American politics:
Working at Northwestern University, psychologists Maureen Craig and Jennifer Richeson apply that question to demographic change, and, in particular, to white Americans vis-à-vis the prospect of a United States where the majority of Americans are drawn from today's minorities. Does a threat to one's status as the demographic "in-group" increase political conservatism? The answer, in short, is yes… [Slate]
Most of the essay explores what happens to whites as they fear losing their demographic preeminence — Bouie concludes it would look a lot like the "racial polarization of the 2012 election" — but at the end he speculates what could happen if people just start voting their race:
With extreme racial polarization — and not the routine identity politics of the present — this goes out the window. We would fracture like the Seven Kingdoms, with a politics governed by mutual suspicion. And you don't have to imagine this future. You can see it right now, in the Deep South, where our history weighs heaviest. In Mississippi, Louisiana, and Alabama, elections are polarized by race: Whites vote one way, blacks the other. The result is constant acrimony, huge disinvestment in public goods like education and health, and a political culture where the central question isn't "how can we help each other" but "how can I stop them from taking what I have."
It's destructive, dangerous, and — as far as America's future goes — more likely than you think. [Slate]
Though this is only tangential to Bouie's piece, the effects of full-blown racialized voting would probably be even worse than that. The biggest reaction, and possibly worst, would be galloping corruption.
South Africa is a country where such a racialized situation exists. In every election since 1994, blacks have voted overwhelmingly for the African National Congress, while whites and Coloureds (the local, nonoffensive term for mixed-race folks) tend to vote for the Democratic Alliance. It's easy to understand why this is the case: the ANC is the party of Nelson Mandela and gets much of the credit for ending apartheid.
But because blacks are about 80 percent of the population, the ANC has won every election since 1994 with over 60 percent of the vote. A lack of a credible opposition party is the single greatest problem with modern South Africa; the absence of discipline created by close elections has led directly to massive corruption and poor governance. Many public schools, especially in the former Bantustan "homelands," are basically worthless.
The lack of competition has poisoned the ANC itself worst of all, which went from an organization of national liberation to "just another grubby political party on the make," largely captured by the wealthy business establishment and increasingly resorting to cheap race-baiting to win votes.
These problems can be stacked right on apartheid's doorstep; the long-term political side effects are one of the most insidious legacies of of colonial-style governance. But that doesn't change the fact that ultimately, a society that votes along demographic lines — which chooses a new government by effectively just totting up the populations of the various ethnic groups — is one which has forfeited much of its democratic character.
There are some positive signs for South Africa, at least: Elections are to be held next month, and the ANC will probably have its worst showing since 1994. Nelson Mandela is gone and the a new generation with no memory of apartheid can vote for the first time. Blacks are increasingly disillusioned with the ANC's poor performance, and the DA's vote share has been increasing sharply.
But it would be bad news indeed if the U.S. had to go through such a process to figure out how bad would be. White folks: Don't panic. America ain't going anywhere.